In an image forming apparatus such as a copying machine, a printer, or a compound machine (a multi-functional peripheral (MFP)) employing an electrophotographic system, an exposing device is used in order to form an electrostatic latent image on a photoconductive drum. If a line-type LED exposing unit including LEDs as light-emitting devices is used as the exposing device, it is possible to reduce the height of the image forming apparatus and provide a compact apparatus.
When the photoconductive drum (or a photoconductive unit in which the photoconductive drum is housed) is detached during maintenance or the like, the line-type LED exposing unit needs to be once separated from the photoconductive drum before the photoconductive drum is detached. Further, if the lens surface of the line-type LED exposing unit is cleaned, the line-type LED exposing unit needs to be separated from the photoconductive drum.
Meanwhile, a gap between a magnet roller incorporated in a developing unit and the photoconductive drum needs to be set to a predetermined short distance. Therefore, if the developing unit is detached during maintenance or the like, the developing unit needs to be once separated from the photoconductive drum before the developing unit is detached.
As a method of bringing the line-type LED exposing unit and the developing unit close to the photoconductive drum during operation, a method of pressing the line-type LED exposing unit and the developing unit in a direction toward the photoconductive drum via a spacer using a pressing force by an elastic member such as a spring is conceivable. However, in this method, a relatively large force (separation force) equal to or larger than the pressing force of the spring or the like needs to be applied if the line-type LED exposing unit and the developing unit are separated from the photoconductive drum. If a separating mechanism having structure resistible against the separation force is configured, the rigidity of components of the separating mechanism needs to be increased and the number of components of the separating mechanism increases. Further, the costs of the separating mechanism increase.